| //===----------------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef _LIBCPP___ALGORITHM_RANGES_UNIFORM_RANDOM_BIT_GENERATOR_ADAPTOR_H |
| #define _LIBCPP___ALGORITHM_RANGES_UNIFORM_RANDOM_BIT_GENERATOR_ADAPTOR_H |
| |
| #include <__config> |
| #include <__functional/invoke.h> |
| #include <__type_traits/remove_cvref.h> |
| |
| #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) |
| # pragma GCC system_header |
| #endif |
| |
| #if _LIBCPP_STD_VER >= 20 |
| |
| _LIBCPP_PUSH_MACROS |
| #include <__undef_macros> |
| |
| _LIBCPP_BEGIN_NAMESPACE_STD |
| |
| // Range versions of random algorithms (e.g. `std::shuffle`) are less constrained than their classic counterparts. |
| // Range algorithms only require the given generator to satisfy the `std::uniform_random_bit_generator` concept. |
| // Classic algorithms require the given generator to meet the uniform random bit generator requirements; these |
| // requirements include satisfying `std::uniform_random_bit_generator` and add a requirement for the generator to |
| // provide a nested `result_type` typedef (see `[rand.req.urng]`). |
| // |
| // To be able to reuse classic implementations, make the given generator meet the classic requirements by wrapping |
| // it into an adaptor type that forwards all of its interface and adds the required typedef. |
| template <class _Gen> |
| class _ClassicGenAdaptor { |
| private: |
| // The generator is not required to be copyable or movable, so it has to be stored as a reference. |
| _Gen& __gen_; |
| |
| public: |
| using result_type = invoke_result_t<_Gen&>; |
| |
| _LIBCPP_HIDE_FROM_ABI |
| static constexpr auto min() { return __remove_cvref_t<_Gen>::min(); } |
| _LIBCPP_HIDE_FROM_ABI |
| static constexpr auto max() { return __remove_cvref_t<_Gen>::max(); } |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr explicit _ClassicGenAdaptor(_Gen& __g) : __gen_(__g) {} |
| |
| _LIBCPP_HIDE_FROM_ABI |
| constexpr auto operator()() const { return __gen_(); } |
| }; |
| |
| _LIBCPP_END_NAMESPACE_STD |
| |
| _LIBCPP_POP_MACROS |
| |
| #endif // _LIBCPP_STD_VER >= 20 |
| |
| #endif // _LIBCPP___ALGORITHM_RANGES_UNIFORM_RANDOM_BIT_GENERATOR_ADAPTOR_H |